I'm not arguing that they don't have a great deal of power and control over the direction and focus of the company. However, it does seem, especially these days, that their pay is not actually connected to their actions, as we see CEO after CEO destroy value while collected big rewards.
This seems like a completely different point from your previous comment.
The answer is that CEOs can be good or bad just like other types of employees, but (just like other employees) you have to pay market rate to hire one, even if they turn out to be bad.